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How much do house extensions cost? | 2020 cost guide

17th Jan '20 • By Jared Jeffery

Whatever your reason for wanting a house extension, there is one component that you want to nail first. And that is budgeting for it. At the end of this cost guide you should have a clear understanding of every cost associated with a house extension. So let’s begin.

Cost of House Extensions

You can expect to pay between $2000 to $4000 per metre squared, so an 80 square metre ground floor extension will cost between $164,500 to $310,000. There a few factors that will affect your cost such as the quality of your inclusions and chosen construction. 

Are you thinking of getting a house extension in 2020 but want to ensure you can comfortably afford one? Well the good news is that a house extension of the ground floor is significantly cheaper than a second storey addition. Not only can a house extension provide more space for your family, it can work as a fantastic professional space, playroom and just about anything you can imagine! 

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how much does a house extension costArticle Overview:

  • The Benefits of a House Extension 
  • How much does a home extension cost?
  • Estimates of the average house extension:
  • Additional home extension costs:
  • Considerations for your budget: 
  • Finding the right builder for your house extension 
  • House Extension FAQs

The Benefits of a House Extension 

Other than the most obvious benefit of a house extension - more space - there are a number of advantages that come with an extra addition to your home! Three of the biggest benefits are as follows… 

  1. You don’t have to uproot your family, life and possessions to move somewhere else! 
  2. You can transform your home into exactly what you want and like. 
  3. It can be less expensive than moving to a bigger home. 

Before you say “wait a minute, surely moving would be less hassle than having construction happening inside your home,” - here us out. There a number of processes involved with moving. Firstly, putting your beloved home on the market (which can take a LONGGG time to sell). Secondly, the actual packing and moving part (did you know moving is up there with the top three most stressful experiences of a lifetime). We could go on and on, but we think you get the picture! 

How much does a Home Extension cost?

We know, we know, this is what you came for. You want to know how much a home extension actually costs. Well, we cannot define the exact cost of your individual home extension without knowing the size, complexity of the job and chosen materials. The standard cost of your house extension will typically include roofing, insulation, cladding, interior cladding, windows and doors. 

Estimates of the Average House Extension:

  • 60m2 Ground Floor Extension - $20,000 and $75,000 
  • 80 Square Metre Ground Floor Extension - between $164,500 to $310,000 
  • A Second Storey Extension - 50% more than ground floor 

Additional Home Extension Costs:

  • Excavation work
  • Heating and air conditioning 
  • If the extension is a bathroom 
  • If the extension is a kitchen
  • Quality inclusions are more expensive
  • Drawing of plans or council fees
  • Having the extension furnished

Considerations for your Budget: 

Finding the right Builder for your House Extension 

On you can browse through a number of professional builders within your area. As always we strongly recommend ensuring you take a number of quotes, do your research and ask questions. 

Some questions you may like to ask a Builder include: 

  • How long will my job take?
  • Are you insured and holding the relevant qualifications for this job?
  • Do you have references I can check?
  • Do you have examples of similar jobs I can see? 
  • How much will this cost? 

It is also worth noting that if a builder’s quote is significantly less than the other quotes you received and sounds too good to be true - it probably is. This builder may simply be undercutting their competitors quotes by leaving out extra costs and then adding them after work has commenced. This is why you should always plan for every single cost and make sure it is covered in your quote. Additionally, higher quotes may not be a rip off but rather a reflection of the builders experience, reputation and standard of work. Investing in the best possible builder for your house extension is always recommended by the team at However, our site offers builders for every kind of budget. 

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House Extension FAQs

Should I extend my current home or move?

This is a question only you can truly answer, however we have some tips in deciding. If you love the home you're in, have great neighbours and facilities nearby then an extension is a fantastic alternative to moving! Not only is moving extremely stressful but often more expensive and time consuming than adding an extension to your current home. 

Do I need to move out of my home during the construction?

The simple answer is no you do not need to move out during the construction phase of your house extension.  However we would recommend it, particularly if you only need to leave for a couple of weeks. This takes the pressure off you and the builders to ensure the work is safely and promptly carried out. 

What eco-friendly options are there for house extensions?

In order to make your house extension eco-friendly you may wish to use recycled materials, install a water tank (if water is needed), use energy efficient LED light bulbs and consult with your builder on what other options are available. 

Can I DIY a house extension? 

At we believe large projects like a house extension are best left to the experts. However if you are an experienced home improvement DIYer with the right knowledge and tools for the job you may undertake the project or enlist expert help further on in the process. 

Should I hire an Architect or a Builder for my extension?

If you are opting for a complex design for your house extension then an architect would be the best option but will likely enlist a builder to carry out the construction. In most cases builders are more than able to handle the extension process. 

When is the right time to add a Home Extension?

This depends on you and your circumstances. If you have considered all the costs and have a budget equipped to handle the task then there is really no time like the present! However, it is wise to consider your personal and work calendar and opt for a time that is less busy and more flexible to interact with builders and oversee construction.

How much does a House Extension cost?

You can expect to pay between $2000 to $4000 per metre squared, so an 80 square metre ground floor extension will cost between $164,500 to $310,000. There a few factors that will affect your cost such as the quality of your inclusions and chosen construction.

Further Reading:

Cost Guides


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